QUANTITATIVE-ANALYSIS OF OIL REMOVAL FROM COTTON FABRICS THROUGH THE IN-SITU FORMATION OF MICROEMULSIONS BY SOLID-STATE NUCLEAR-MAGNETIC-RESONANCE

Solubilization and subsequent removal of soybean oil from cotton fabri cs through the in situ formation of microemulsions were evaluated by s olid-state nuclear magnetic resonance (NMR) spectrometry. Regions of w ater-in-oil and oil-in-water microemulsions were identified for system s that contained polyoxyethylene (60) sorbitol hexaoleate, soybean oil , and an aqueous phase composed of water/ethanol or isopropanol (80:20 wt%) at 25 degrees C. The amount of oil removed from the cotton fabri cs was determined by solid-state NMR after constructing a calibration curve relating the intensity of camphor/oil NMR signals (IcIo) to thei r molar ratio (M(c)M(o)). A precision Crockmeter (Mul-Tech Industries, New York, NY) was used to reproducibly remove soybean oil stain from cotton fabric, which was subsequently analyzed by NMR. Typically, more than 90% of the oil stain was removed after 200 revolutions of the Cr ockmeter finger with 2 wt% surfactant at 25 degrees C. Increasing the amount of surfactant to 6 wt% improved soybean oil removal from the fa bric to 99 wt%.